mirror of
https://github.com/mytechnotalent/Embedded-Hacking.git
synced 2026-05-19 14:28:06 +02:00
Kevin Thomas
91 lines
3.0 KiB
C
91 lines
3.0 KiB
C
/**
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* @file 0x0014_static-variables.c
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* @brief Static variables: compare regular vs static local variable persistence
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* @author Kevin Thomas
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* @date 2025
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*
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* MIT License
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*
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* Copyright (c) 2025 Kevin Thomas
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* -----------------------------------------------------------------------------
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*
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* Demonstrates the difference between regular and static local variables.
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* A regular variable resets to 42 each iteration while a static variable
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* persists and increments across loop iterations. Also reads a button on
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* GPIO15 and mirrors its state to an LED on GPIO16.
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*
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* Wiring:
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* GPIO15 -> Button (with pull-up, active low)
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* GPIO16 -> LED anode (with current-limiting resistor to GND)
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*/
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#include <stdio.h>
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#include "pico/stdlib.h"
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/** @brief GPIO pin number for the button input */
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#define BUTTON_GPIO 15
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/** @brief GPIO pin number for the LED output */
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#define LED_GPIO 16
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/**
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* @brief Initialize button and LED GPIO pins
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*
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* @details Configures the button pin as input with pull-up and the
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* LED pin as output.
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*
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* @retval None
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*/
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static void init_gpio(void) {
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gpio_init(BUTTON_GPIO);
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gpio_set_dir(BUTTON_GPIO, GPIO_IN);
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gpio_pull_up(BUTTON_GPIO);
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gpio_init(LED_GPIO);
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gpio_set_dir(LED_GPIO, GPIO_OUT);
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}
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/**
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* @brief Print and increment regular vs static variables, update LED
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*
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* @details Prints both variable values, increments them, reads the
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* button state and drives the LED accordingly.
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*
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* @retval None
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*/
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static void demo_static_variable(void) {
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uint8_t regular_fav_num = 42;
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static uint8_t static_fav_num = 42;
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printf("regular_fav_num: %d\r\n", regular_fav_num);
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printf("static_fav_num: %d\r\n", static_fav_num);
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regular_fav_num++;
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static_fav_num++;
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bool pressed = gpio_get(BUTTON_GPIO);
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gpio_put(LED_GPIO, pressed ? 0 : 1);
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}
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int main(void) {
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stdio_init_all();
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init_gpio();
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while (true) {
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demo_static_variable();
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}
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}
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